ROUTERS

Presented to:-Sir.AliPresented by:-Mahmood Khan

Roll No:-2801

Objectives:-1. What is a Router?2. Introduction

t0RoutingFundamentals.3. Router Modes.4. Router Interfaces.

What Is Router?

1. A Router is a device that connects two

networks - frequently over large distances.

It understands one or more network

protocols, such as IPor IPX. A Router

accepts packets on at least two network

interfaces, and forwards packets from one

interface to another.

Routing FundamentalsRouters examine a packet’s destination IP

address and determine the best path by enlisting the aid of a routing table

Routing Fundamentals :Routers and the Network Layer

– Routers use destination IP address to forward packets

• The path a packet takes is determined after a router consults information in the routing table

• After router determines the best path• Packet is encapsulated into a frame• Frame is then placed on network medium in form

of Bits

Routing Fundamentals CONT….Routers Operate at Layers 1, 2 & 3

– Router receives a stream of encoded bits– Bits are decoded and passed to layer 2– Router de-encapsulates the frame– Remaining packet passed up to layer 3

• Routing decision made at this layer by examining destination IP address

– Packet is then re-encapsulated & sent out outbound interface

Router Hardware FundamentalsRouter components and their functions:

– CPU - Executes operating system instructions– Random access memory (RAM) - Contains

the running copy of configuration file. Stores routing table. RAM contents lost when power is off.

– Read-only memory (ROM) - Holds diagnostic software used when router is powered up. Stores the router’s bootstrap program.

– Non-volatile RAM (NVRAM) - Stores startup configuration. This may include IP addresses (Routing protocol, Hostname of router).

– Flash memory - Contains the operating system (Cisco IOS).

– Interfaces - There exist multiple physical interfaces that are used to connect network. Examples of interface types:

• Ethernet / fast Ethernet interfaces• Serial interfaces• Management interfaces

Router Modes

Router InterfacesRouter Interface is a physical connector that

enables a router to send or receive packetsEach interface connects to a separate

networkConsist of socket or jack found on the outside

of a router Types of router interfaces:

– Ethernet– Fastethernet– Serial– DSL– ISDN– Cable– Console– Aux–

Router InterfacesTwo major groups of Router Interfaces

– LAN Interfaces• Are used to connect router to LAN network• Has a layer 2 MAC address • Can be assigned a Layer 3 IP address• Usually consist of an RJ-45 jack

– WAN Interfaces• Are used to connect routers to external networks that

interconnect LANs• Depending on the WAN technology, a layer 2 address may be

used• Uses a layer 3 IP address

Eathernet 1. Ethernet is a family of computer networking technologies for

local area networks (LANs). Ethernet commercially introduced in

1980 and standardized in 1985 as IEEE 802.3. Ethernet has largely

replaced competing wired LAN technologies.

2. Systems communicating over Ethernet divide a stream of data into

shorter pieces called frames. Each frame contains source and destination

addresses and error-checking data so that damaged data can be detected

and re-transmitted. As per the OSI model Ethernet provides services up to

and including the data link layer.

Fast Ethernet

" Fast Ethernet port works with 100 Mbps and Ethernet port works with 10 Mbps ”

ISDN

Integrated Services Digital Network

(ISDN) is a set of communication

standards for simultaneous digital

transmission of voice, video, data, and

other network services over the

traditional circuits of the public switched

telephone network. The telephone

system was viewed as a way to transport

voice, with some special services

available for data. The key feature of

ISDN is that it integrates speech and

data on the same lines, adding features

that were not available in the classic

telephone system. There are several

kinds of access interfaces to ISDN

defined as Basic Rate Interface (BRI),

Primary Rate Interface (PRI) and

Broadband ISDN (B-ISDN).

DSL Multiple devices have been described as "residential gateways," each with a different

function. Each type of device allows the connection of a LAN (used in the home) to a WAN.

The WAN can often be the Internet or can merely be a larger LAN of which the home is a

part (such as a municipal WAN that provides connectivity to the residences within the

municipality). WAN connectivity may be provided through DSL, cable modem, a

broadband mobile phone network, or other connections.

ConsoleThis is use to configure the router.

Aux• It is use to connect the router with remote access

device/modem

• remotely access from other location.

Serial/WAN (Wide Area Network port) The socket on a network device that is wired to an

external network such as the Internet. In the home and small business, a WAN port

is typically an Ethernet port on a router that is wired to its counterpart port on a

cable or DSL modem. In the larger enterprise, a WAN port may hook up to a T1 line

or other wide area network service and use a V.35, RS-232 or RS-530 connection.

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